Integrally molded surface fastener, and continuous production method and continuous production device therefor

ABSTRACT

In a molded surface fastener ( 10 ) having engaging elements ( 2 ) of minute dimension of thermoplastic resin molded together with a base member ( 1 ) by continuous molding, each engaging element ( 2 ) comprises first and second engaging portions ( 22   a,    22   b ) each having a different configuration extending in parallel to a surface of the base member from a top end of a pillar portion ( 21 ) rising from the base member ( 1 ) such that they intersect at right angle. The second engaging head ( 22   b ) has an ordinary hook shape structure while the first engaging head ( 22   a ) has a wing-like thin plate structure as seen in a plan view. The engaging elements having such a structure in which each engaging element has appropriate engagement force, shearing force and separation force so as to keep an excellent tactile feeling of a surface of the surface fastener, prevents itself from falling down against a pressing force, secures a high engagement ratio with mating pile pieces and satisfies a durability.

TECHNICAL FIELD

The present invention relates to a surface fastener obtained by moldinga flat base member and a number of engaging elements integrally andcontinuously using thermoplastic resin, a production method andproduction device therefor, and more particularly to an integrallymolded surface fastener in which the engaging elements are unlikely tofall down despite their fine dimension and engage minute pile pieces ofunwoven fabric securely so as to secure a specified engaging force, aseparation force and a high engagement ratio, this integrally moldedsurface fastener being capable of enduring several engaging/disengagingoperations sufficiently, and preferably applied to paper diaper, medicalsimple clothing, napkins, various kinds of working simple clothing,underwear and the like, and a production method and production devicetherefor.

BACKGROUND ART

In recent years, as a fastening device for disposable paper diaper,medical simple clothing, napkins, various kinds of working simpleclothing, underwear and the like, the surface fasteners each having anumber of engaging elements of minute dimension molded integrally with aflat base material by continuous injection molding of thermoplasticresin have been often used. The configuration of the engaging element ofthe integrally molded surface fastener of this kind is classifiedlargely to hook type and mushroom type as well known in the relatedfield.

Typical hook type integrally molded surface fasteners have beendisclosed in, for example, U.S. Pat. No. 4,984,339 and U.S. Pat. No.5,537,723. In case of these molded surface fasteners, molten resin issupplied to the circumferential face of a cylindrical drum in which anumber of substantially letter J shaped cavities are formed such thatthey are open to the circumferential face in a curved configuration frominside of the drum so as to mold a thin base material along thecircumferential face while at a time, an inverted letter J shaped hookis molded integrally with the rear face of the base material by fillingthe cavity with part of molten resin. After cooling, a molded product isproduced by peeling it from the circumferential face of the drum.

An integrally molded surface fastener having a modified configuration ofthe aforementioned hook type engaging element has been also disclosedin, for example, Japanese Patent Laid-Open Publication No. 2-5947 andJapanese Patent Laid-Open Publication No. 6-133808. Upon production ofthe molded surface fastener, molten resin is extruded from an extrusiondie having a number of openings erected in the form of substantially twoleaf palm tree or letter T on a narrow slit extending horizontally, sothat a number of rows of ribs having palm tree shaped or letter T shapedsection in the extrusion direction are molded continuously on a thinbase member so as to produce a primary molded product. Next, the rib ofthe primary molded product is cut out successively by a predeterminedthickness along the length direction and then, palm tree shaped orletter T shaped engaging elements are fit thereto. After that, the basemember is extended in the molding direction so as to separate therespective engaging elements by a predetermined pitch so as to product amolded surface fastener having a final configuration.

More recently, molded surface fasteners having a novel hookconfiguration in which the aforementioned hook type engaging elementconfiguration is modified largely have been developed. Those moldedsurface fasteners have been disclosed in, for example, Japanese PatentLaid-Open Publication No. 9-322812 and Japanese Patent Laid-OpenPublication No. 11-56413. The engaging element of these publicationscomprises an erecting portion which erects upward from the surface ofthe base member, a neck portion which separates in the molding directionwith a V-shaped gap at the top end of the erecting portion and engaginghead extending substantially horizontally back and forth in the moldingdirection from each neck portion. Further, the bottom face of theengaging head is inclined obliquely upward as it goes toward the frontend and its top face is a flat plane and in a front view along themolding direction, expanded portions each having a predeterminedthickness in the vertical direction are provided on the right and leftsides of the top face.

As its basic production method, the primary molding technology using theaforementioned cylindrical drum has been adopted. However, the engagingelement molded on the surface of a base member upon molding is notmolded in the form of letter J from the beginning, but in a side viewalong the molding direction, a primary engaging element material havingtwo V-shaped or four cross-shaped branches extending upward in aninclined state at the top end of its erected portion is moldedpreliminarily, so that a preliminarily molded surface fastener in whicha number of the primary engaging element materials are molded integrallyon the base member is produced. Then, by pressing the branch portions ofthe primary engaging element materials of the preliminarily moldedsurface fastener with heat, the top portion is softened and deformed tomold engaging elements having peculiar configuration, which theconventional art has never seen.

On the other hand, the mushroom type molded surface fastener has beenalso well known since before and according to for example, U.S. Pat. No.3,192,589, after the preliminarily molded surface fastener in which anumber of pillars are erected on the surface of the base member ismolded, the front ends of the pillars of the molded product is softenedby heating so as to mold semi-spherical engaging heads for manufacturingof the molded surface fastener. For example, Japanese Patent Laid-OpenPublication No. 8-508910 has disclosed an improvement technology of themushroom type molded surface fastener. According to the molded surfacefastener disclosed in this publication, the front ends of the pillars ofthe primary molded product are softened by pressing and heating so as tomold circular plate engaging heads instead of the semi-sphericalengaging heads.

Because the aforementioned mushroom type engaging element engages in alldirections, it has been known that it has stronger engaging strength andseparation strength than the hook type engaging element whose engagementhas a directivity. However, because in the engagement mechanism of thepile to the mushroom type engaging element, the pile engages inso-called hanging condition that it winds up around the neck portion, ifit is intended to release the pile from the engaging head, theprobability that the engaging element may be cut out or the pile itselfmay be cut out at the neck portion is high, so that this often cannotbear repeated usage and at a time, the engaging strength and separationstrength likely increase excessively.

The molded surface fastener disclosed in the aforementioned JapanesePatent Laid-Open Publication No. 8-508910 is an improvement based on theadvantages and disadvantages of the mushroom type and intensifies theengagement ratio to minute piles by forming the shape of the engaginghead into a substantially circular shape while securing an appropriateseparation strength. This can be adopted as a fixing device to variouskinds of unwoven minute piles, which are attached to the aforementioneddisposable diaper. The application of such fixing device has beenexpanding rapidly as described above, and a further improvement has beenstill proposed in, for example, International Publication No. 98/57565pamphlet. That improvement aims at intensifying the plasticity of theengaging head by forming much minute unevenness on the top face of thecircular engaging head.

On the other hand, as compared to the mushroom type engaging element,the aforementioned hook type engaging element is more likely to engagethe pile and further, obtain appropriate engagement strength andseparation strength. At the time of separation, the engaging elementsand piles are never cut out and can bear repeated usage. In addition tothe aforementioned Japanese Patent Laid-Open Publication No. 6-133808and Japanese Patent Laid-Open Publication No. 9-32281, for example,Japanese Patent Application No. 2001-6440 filed by these inventors hasproposed an integrally molded surface fastener to adopt such advantagesof the hook type for the fixing device of the disposable diaper and thelike.

This integrally molded surface fastener is a molded surface fastenerhaving minute engaging elements of thermoplastic resin which are moldedtogether with the base member by continuous molding. The engagingelement is composed of a single pillar portion comprising first andsecond pillar portions which intersect with each other at right anglehaving a substantially cross shaped section. The pillar portions extendin opposite directions to each other in a wing-like form along theintersection directions of the first and second pillar portions withrespect to the top end of the pillar portion and have a thin engaginghead having substantially the width as the width of the top end of thesecond pillar portion.

If such minute engaging elements having the peculiar head configurationare molded, securely they engage fiber piles planted densely andindividual engaging elements can secure appropriate engaging force,shearing force and separation force and at a time, the tactile feelingof the surface fastener is improved. The height of the engaging elementprojecting from the surface of the base member can be reduced ascompared to conventional type. On the other hand, because the sectionalshape of the pillar portion is formed into a cross shape as describedabove, the engaging element is blocked from falling down against apressing force so as to secure a high engagement ratio with mating pilepieces. Consequently, a durability demanded to this kind of the fixingdevice is satisfied and desired plasticity and shearing strength of theflat base member can be secured.

According to the production technology of the hook type molded surfacefastener disclosed in the aforementioned Japanese Patent Laid-OpenPublication No. 6-133808, a number of ribs erected on the base member ofa preliminarily molded surface fastener molded primarily are cut outsuccessively by a predetermined pitch along the length direction and itsbase member is stretched in the length direction (molding direction) soas to separate individual engaging elements to a predetermined interval.Therefore, the thickness in the molding direction of the engagingelement is determined by a cutting pitch and its stiffness is determinedby the material and cutting thickness of used resin. Thus, if it isintended to obtain engaging elements which engage/disengage minute pileslike for example, unwoven cloth surface according to such a productionmethod, naturally the thickness in the molding direction becomes verysmall, so that they are likely to buckle in the molding direction. Thus,the stiffness cannot be improved until the thickness is increased.

In case of the molded surface fastener having the hook type engagingelements based on the aforementioned Japanese Patent Laid-OpenPublication No. 9-322812 or Japanese Patent Laid-Open Publication No.11-56413, although the fall-down of the erected portion decreases andthe engagement ratio is secured because of the peculiar shape of theengaging element, necessary separation strength is more difficult toobtain as the minuteness progresses and increase in the separationstrength to the disposable diaper and the like has been stronglydemanded as described above. As compared to the engaging elementaccording to the Japanese Patent Application No. 2001-6440, although ahigh engagement ratio with a mating pile piece is secured by preventingthe fall-down of the engaging element against a pressing force, so thatthe durability required for this kind of the fixing device is satisfiedand desired plasticity and shearing strength of the flat base member canbe secured, it cannot be said that its engaging force and separationstrength are sufficient.

On the other hand, in case of the molded surface fastener having themushroom type engaging element disclosed in the aforementioned JapanesePatent Laid-Open Publication No. 8-508910 or International PublicationNo. 98/57565 pamphlet, despite its minuteness, the root portion havingan arbitrary size can be molded to provide with a required stiffnesswhich prevents its buckling. However, if it is intended to provide theroot portion with a desired stiffness, the size of the root portioncannot help being increased.

If the diameter of the root portion increases, even if the extendinglength of the engaging head which extends from the root portion to alldirections is to be minute, necessarily the diameter of the engaginghead increases by the amount corresponding to the increase in thediameter of the root portion, so that no minute engaging element can bemolded and if it is molded in a large size, naturally it is difficult toengage a loop. Further, even if the engaging element is molded in aminute size, the so-called hanging, which occurs in the mushroom fromthe peculiar configuration, cannot be avoided and it is cut out easilybetween the pillar portion and the engaging head or the mating pile iscut out easily. Thus, it is difficult to secure a necessary durability.

As for a problem which this kind of the integrally molded surfacefastener faces, if it is used as a disposable paper diaper, medicalsimple clothing, napkins, various of working clothing, underwear and thelike, an engaging object becomes extremely minute piles exposed on thesurface of ordinary unwoven cloth or knitted fabric, necessarily, thesize of the engaging element of the integrally molded surface fastenerneeds to be small and particularly, because there is much opportunitythat it makes contact with soft skin of infant, the engaging elementneeds to have mild tactile feeling as well as plasticity. Further, thisengaging element needs to bear repeated usage of two or three timessufficiently although it is disposable and at a time, the separationstrength needs to be high enough for the diaper not to loose out easily.

In case of a conventional integrally molded surface fastener, theengaging element can be molded in minute sizes, and for example, in caseof the mushroom type engaging element, its separation strength is toohigh so that the minute pile or engaging element itself is likely to bedamaged at the time of separation. In case of the hook type engagingelement, there is a problem that a desired separation strength cannot besecured although it never damage the minute piles or engaging elementsitself.

DISCLOSURE OF THE INVENTION

The present invention has been accomplished to solve these diversifiedproblems and an object of the invention is to provide an integrallymolded surface fastener which is capable of engaging minute dense fiberpiles composed of unwoven fabric or knitted fabric in all directionssecurely, provides individual engaging elements with appropriateengaging force, shearing force and separation force, has an excellenttactile feeling on the surface of the surface fastener, secures a highengagement ratio with mating pile pieces, satisfies a durabilitydemanded for this kind of fixing device and secures desired plasticityand tear strength of its flat base member, a production method thereforand a production device therefor.

Such an object is achieved by an integrally molded surface fastener ofsynthetic resin in which a number of fine engaging elements, whichengage/disengage a mating pile piece, are molded integrally on a surfaceof a flat base member, be characterized in that each engaging elementcomprises a pillar portion having a predetermined height and an engaginghead composed of first and second engaging portions, which extend from atop end of the pillar portion along the surface of the base member in afirst direction and in a second direction different from the firstdirection, and the first and second engaging portions have differentshapes.

According to the present invention, the engaging head formed at the topend of the pillar portion comprises first and second engaging portionsextending in first and second directions along the surface of the basemember. That is, if the first and second engaging portions are seen in aplan view, while the first engaging portion extends vertically in theform of L shape or cross shape, there are two or more second engagingportions extending in a different direction from the first engagingportion. Further, according to the present invention, the shapes of thefirst and second engaging portions are different. For example, asstipulated in claim 2, the first engaging portion is composed ofwing-like thin plate and the second engaging portion is composed ofordinary hook piece. Of course, they may be formed in inverseconfigurations and the shape of the hook piece may be of substantiallyletter V or letter T as well as of inverted letter J. Further, it ispermissible that the top face of the substantially letter V or letter Tshaped element is a flat plane and expanded portions extend from sideedges perpendicular to that extending direction.

The wing-like thin plate mentioned in the present invention refers to athin plate of an ½ elliptic shape, rectangular shape or triangular shapewhose front end is a sharp angle. The present invention may be formed ina substantially letter L shape as seen in a plan view such that thewing-like thin plate is formed to extend in one direction from the topend of the pillar portion and the second engaging portion having thehook shape extends in the other direction from the top end of the pillarportion, intersecting with the wing-like thin plate. Alternatively, thepresent invention may be formed in a substantially cross shape such thatthe wing-like thin plate and the second engaging portion extend inopposite directions to each other across the top end of the pillarportion. Further, two or more second engaging portions may be extendedin parallel such that they intersect the wing-like thin plate.

The shape of the wing-like thin plate as seen in a side view may bedecreased gradually from the proximal end to the front end in thicknessinstead of simply being linear and particularly, the bottom face may beformed into an inclined face which is inclined obliquely upward.Although the extension length and width dimension can be determinedarbitrarily, they are changed depending on the relation with the widthof the top end of the pillar portion or the size or shape of a pile onthe surface of unwoven fabric which is a mating object. In the meantime,the height of the pile projecting from the surface of unwoven fabric orknitted fabric for use in the pile engaging portion of disposable paperdiapers or the like is extremely minute, that is, about 0.35 to 1.1 mm.

Thus, if the engaging head is formed in a thickness as small as possibleand its width is set to a small one, the engaging head can be allowed toinvade into the minute pile. However, if the thickness of the engaginghead is excessively small and the width is too small, it is difficult toobtain a desired engagement strength or separation strength. Thus, it isvery important to control the thickness and width arbitrarily. Forexample, the thickness in the vertical direction of the front end of theengaging head can be formed smaller than the proximal end and in thiscase, it not only likely invades into the mating pile but also if thepile is engaged, the engagement strength and separation force increasebecause the thickness in the vertical direction of the engaging headnear the proximal end is large. As for the engagement style between theengaging element and pile of the present invention, the pile winds uparound the first and second engaging portions in pair extending in bothways with respect to the pillar portion at a time, often engaging themby hooking on the pillar side of engaging head. Because the wing-likethin plate and hook plate are supported by the pillar portion in acantilevered style, it looses out from the pile relatively easilydifferent from the mushroom type.

The front end of the wing-like thin plate of the first engaging portioncan be curved toward the surface of the base member. Although the basicconfiguration of the wing-like thin plate is a horizontal thin plate,according to the present invention, the front end of the wing-like thinplate is curved downward. Due to this curve, an engaging pile is hookedby that curved portion thereby the engagement strength and separationstrength being increased. Further, the central portion of the top faceof the engaging head composed of the first and second engaging portionsis preferred to be dented slightly with respect to the other top faceportions. Due to this dent, when it is intended to remove a pileengaging the engaging element, it is easy to bent across a borderbetween the dent portion and the engaging head extending from the firstpillar portion. Even if the proximal end portion of the engaging head isthick in the vertical direction, the pile can be removed from theengaging head easily and a necessary separation strength can beobtained.

The pillar portion is preferred to have a horizontal section whichintersects with the first and second engaging portions in a samedirection. The pillar portion may be formed such that its sectional areadecreases gradually from the proximal end to the top end. Becauseaccording to the present invention, when the pillar section provides asubstantially cross shape or letter L shape, the stiffness in the xdirection and y direction which intersect with each other at right angleincreases, even if the quantity of used material is reduced, difficultyof being buckled is not inferior to a square section whose side has thedimension as the width of the first and second pillar portions or apillar portion having a circular section whose diameter is the as thewidth.

However, if the pillar portion is constructed of a mere rectangularpillar portion, when it is pressed from above in order to make itengaged the mating pile or remove the pile in engagement, the pillarfalls down at its root easily. Thus, preferably, by decreasing thesectional area of the pillar portion gradually toward the engaging head,the stiffness of the proximal end side is increased to make it difficultto fall down.

Preferably, the base member is formed with a dented portion between theadjacent pillar portions in the molding direction of the base member,not formed of a mere flat plate. When the engaging element is raisedfrom the bottom face of the dented portion, even if the distance betweenthe bottom face of the front end of the engaging head and the startingpoint of the pillar portion (bottom face in the dented portion) is setto the as conventionally, the distance from the bottom end of the frontend of the engaging head and the surface of the base member except thedented portion becomes identical to a difference between an actualheight from the proximal end of the pillar portion and the depth of thedented portion. Thus, although the actual height of the engaging elementerected from the base member is identical to the conventional type, anapparent height projecting from the surface of the base member is ashort dimension obtained by subtracting the depth of the bottom face ofthe dented portion. Further, if the dented portion is formed in thesurface of the base member, the plasticity of the base member isimproved remarkably even if the apparent thickness is same as theconventional type, and further when the surface fastener is peeled outof the molding die after the molding is finished, the base member is notstretched excessively or torn out but it can be peeled out stably.

As a result, the base member in a molded product is never waved andthus, a high quality product bearing actual use sufficiently can beobtained. If the height of the pillar portion from the bottom face ofthe dented portion is substantially ⅕ to ⅘ the height from the bottomface up to the vertex of the front end of the engaging head, the pillarportion becomes difficult to fall down because a portion projecting fromthe surface except the dented portion of the base member of the pillarportion is relatively low, thereby stabilizing the configuration at thetime of engagement. Further, if the dented portion has a width allowingthe mating pile to be introduced, the engagement ratio with the pileincreases.

As for the preferred dimensions of the engaging element of the presentinvention, the length between the vertex of the front end of theengaging head and the surface of the base member is 0.1 to 1.2 mm, theextending length of the engaging portion from the pillar portion is 0.2to 0.5 mm and the height of the pillar portion from the surface of thebase member is 0.005 to 1.0 mm. These numerical ranges are basicnumerical ranges which are sufficient for securing an engagement withthe pile piece (pile) having the minute configuration which is anengagement object of the present invention and are ranges which provideno rigidity feeling at the time of engagement or disengagement.Particularly, their lower limits are values which enable secureengagement to even fiber piles having the finest configuration ofordinary unwoven fabric.

As for the arrangement of the engaging elements having theabove-mentioned configuration on the base member, the first and secondengaging portions are disposed perpendicularly to the molding directionof the base member while the second engaging portion is disposed inparallel to the molding direction of the base member. However, the firstengaging portion may be disposed in parallel to the molding direction ofthe base member and the second engaging portion may be disposedperpendicularly to the molding direction of the base member. To directthe engaging head in two different directions, in the molding directionand in a direction perpendicular to that direction, according to theinvention about the production method described later, this is achievedby forming the first and second engaging portion molding cavities byturning around them by 90°.

As a result, the first and second engaging portions whose extendingdirections are altered by 90° are disposed mixedly in terms of themolding direction on the base member. By disposing engaging elementswhose first and second engaging portions are directed in two directions,the molding direction and in a direction perpendicular to that directionmixedly, the engagement ratio to the mating pile is improved. Thearrangement style can be determined in an arbitrary way, the engagingelements can be disposed alternately in matrix on the surface of thebase member or in a staggered fashion.

The molded surface fastener comprising the engaging elements having sucha configuration can be produced easily and effectively according to thefollowing continuous production method. That is, the production methodis characterized by comprising: rotating a cylindrical drum in onedirection, the cylindrical drum having a number of preliminarily moldedelement molding cavities each composed of a main cavity which is open ina circumferential face and extends linearly up to a predetermined depthand a second engaging portion molding cavity which is not open in thecircumferential face and is branched from halfway of the main cavity andextends in a molding direction or in a lateral direction with respectthereto; injecting molten resin continuously to the circumferential faceof the cylindrical drum, molding the base member along thecircumferential face while molding a number of preliminarily moldedelements on a back side of the base member such that they erect upright;peeling a belt-like preliminarily molded surface fastener from thecircumferential face of the cylindrical drum, the preliminarily moldedsurface fastener having the preliminarily molded elements on the basemember which moves carried by the circumferential face of the rotatingcylindrical drum; feeding the preliminarily molded surface fastenerpeeled continuously to a with-heat pressing portion; and pressing atleast a preliminarily molded first engaging portion erected linearly ofthe preliminarily molded portions erected integrally from the surface ofthe base member of the carried preliminarily molded surface fastenerwith heat, melting and deforming into a flat wing-like thin plate so asto mold the first engaging portion successively.

The most prominent configuration of this production method exists in theshape of the cavity formed in the circumferential face of thecylindrical drum and the shape of the preliminarily molded element ofthe engaging element molded by the cavity. As for the shape of thispreliminarily molded element, no preliminarily molded material erectedwith the section is molded from the back side of the base member likemolding of the conventional mushroom type but this preliminarily moldedmaterial comprises a preliminarily molded pillar portion having anarbitrary section on the proximal end side of the preliminarily moldedelement, a preliminarily molded first engaging portion erected linearlyand continuously at that portion and a hook piece which is apreliminarily molded second engaging portion branched and extending fromthe top end of the preliminarily molded pillar portion.

Further, the present invention may include a case where thepreliminarily molded first engaging portion is melted and deformed intoa flat wing-like thin plate by pressing with heat with the with-heatpressing portion while the top end of the preliminarily molded secondengaging portion is also melted and deformed at a time. In this case,although the configuration of the preliminarily molded second engagingportion may be curved in the form of a hook such that its front endfaces downward from the beginning when it is branched from thepreliminarily molded pillar portion, it is preferred to rise obliquelyupward linearly and then branch. When molding into a linearconfiguration, the top end of the preliminarily molded second engagingportion is heated under a pressure by the with-heat pressing portionwhile its proximal end is curved, so that the top surface from the frontend to the center is melted and deformed into a flat hook shape. Due tosuch a configuration, a predetermined engagement force with a matingpile can be obtained although it is smaller than a complete hook type.

On the other hand, the distance between the top end of the preliminarilymolded second engaging portion and the surface of the base member ispreferred to be shorter than the distance between the top end of thepreliminarily molded first engaging portion and the surface of the basemember. The difference in distance from the base member to the top endof both the preliminarily molded first engaging portion and thepreliminarily molded second engaging portion is determined by thelength, width, thickness and the like of the first engaging portionextending from the pillar portion obtained by following molding. Thethickness and extension length of the first engaging portion can becontrolled by controlling the amount of resin in the preliminarilymolded first engaging portion and the quantity of deformation due topressing at the time of the heating under a pressure. Further, theextension direction of the first engaging portion can be changedarbitrarily by selecting the molding direction or the directionperpendicular to the molding direction as the direction of its long sidewhen the sectional shape of the pillar portion is rectangular.

This preliminarily molded element is molded into an engaging elementhaving the aforementioned peculiar configuration by melting anddeforming the preliminarily molded first engaging portion substantiallyup to the top end of the preliminarily molded pillar portion byfollowing heating under pressure. Thus, the preliminarily molded pillarportion itself is not melted and deformed so much but maintains itsoriginal shape to turn to a pillar portion of a subsequent engagingelement. The preliminarily first engaging portion extending upwardlinearly from the top end is melted and deformed by heating underpressure and the first engaging portion composed of a substantiallywing-like thin plate is molded. The preliminarily second engagingportion branched and extending sideway from the top end of thepreliminarily molded pillar portion is sometimes melted and deformed byheating under pressure or sometimes is not influenced by heating underpressure depending on its molding configuration.

Such a method is executed through continuous production with anintegrally molded surface fastener production device of the presentinvention. That device comprises: a cylindrical drum rotating in onedirection and having a number of preliminarily molded element moldingcavities composed of a main cavity which is open in a circumferentialface and extends up to a predetermined depth and a second engagingportion molding cavity which is branched from halfway of the main cavityand extends in a molding direction; a continuous injecting unit whichinjects molten resin continuously to the circumferential face of thecylindrical drum so as to mold the base member along the circumferentialface, and molds a number of preliminarily molded elements on a back sideof the base member such that they are erected upright; a take-up meansfor peeling a belt-like preliminarily molded surface fastener from thecircumferential face of the cylindrical drum continuously, thepreliminarily molded surface fastener having the preliminarily moldedelements on the base member which moves carried by the circumferentialface of the rotating cylindrical drum; and a with-heat pressing portionwhich presses with heat at least a preliminarily molded portion erectedlinearly of the preliminarily molded elements erected integrally fromthe surface of the base member of the peeled preliminarily moldedsurface fastener so as to melt and deform into a wing-like thin plate tomold the first engaging portion successively.

The with-heat pressing portion comprises an internal heating unitcontaining a carrying face for the preliminarily molded surface fastenerand a pressing rotation roll containing a rotation shaft which isincluded in a plane above and in parallel to the carrying face andextends in a direction perpendicular to the moving direction of thepreliminarily molded surface fastener, wherein a gap between the bottomend position of the pressing rotation roll and the carrying face is setas same as a dimension gained by adding the setting dimension in thevertical direction of the first engaging portion to a sum of thedimensions in the vertical direction of the base member and said pillarportion. The internal heating unit mentioned here refers to a unit whichaccompanies internal heat generation due to moving of molecules inmaterial itself without heating resin material which become meltingobject from outside, such as ultrasonic heating unit and high frequencyheating unit. By disposing the continuous injecting unit, thecylindrical drum, the take-up means and the with-heat pressing portioncontinuously, a molded surface fastener of the present invention inwhich a number of engaging elements having the above-describedembodiment are molded integrally on the continuous base member can beproduced effectively and continuously.

Further, the present invention includes a with-heat pressing memberwhich is disposed above the carrying face and has an inclined face inwhich the gap between the bottom face and the carrying face decreasesgradually in the direction of fastener, instead of the pressing rotationroll, and a gap of the narrowest portion between the carrying face andthe inclined face is as same as a dimension gained by adding the settingdimension in the vertical direction of the second engaging portion to asum of the dimensions in the vertical direction of the base member andthe pillar portion.

If the minimum gap between the pressing face of the with-heat pressingportion and the surface of the base member is set as described above,the engaging head having the above-described configuration is formedcontinuously only by introducing a preliminarily molded surface fastenermolded on the rotation drum into the with-heat pressing portion andallowing it to pass. Although the minimum gap between the pressing faceand the inclined face portion of the pressing rotation roll and thesurface of the base member is set identical to the thickness of thefirst engaging portion whose thickness in the vertical direction is setup when the preliminarily molded first engaging portion is deformed bypressing, if the gap is slightly larger, a region on the border betweenthe preliminarily molded first and second engaging portions and thepreliminarily molded pillar portion is not melted or deformed, to securea neck portion between the pillar portion and the engaging head.

Needless to say, a case where such a neck portion is formed is includedin the technical scope of the present invention. If the neck portion ismolded between the pillar portion and the engaging head, when it isintended to remove a mating pile wound around the neck portion uponengagement, the neck portion swings so as to incline the pile in theseparation direction, facilitating the removal of the pile as comparedto a case where no neck portion exits, thereby preventing the pile frombeing cut out meaninglessly.

If the heating temperature of the with-heat pressing portion is set nearthe melting point of the resin material or the time for heating withpressure on the preliminarily molded surface fastener is prolonged, theextending side ends of the engaging head are softened more so that theydroop downward with curve by their own weight, thereby increasing theengagement force with the mating object.

In the production of the molded surface fastener of the presentinvention, for molding of the preliminarily molded surface fastener,preferably, a cooling means is incorporated in a cylindrical drum or apreliminarily molded surface fastener accompanying region of thecylindrical drum is immersed into a cooling bath so as to coolaggressively and the molded surface fastener, after passing thewith-heat pressing means, is wound up after cooled gradually under thenormal temperature without cooling aggressively by specific coolingmeans. As the engaging head softened and deformed with heat is cooledgradually and solidified, the heated portion is crystallizedprogressively so that the stiffness of the engaging head becomes higherthan that of the pillar portion. At this time, a heating range, heatingtime and heating temperature can be controlled appropriately dependingon the dimension and modified shape of the engaging element.

In case of the integrally molded surface fastener cooled and solidifiedrapidly without progressive crystallization between the base member andthe pillar portion of the preliminarily molded element, the base memberand pillar portion maintain plasticity and the stiffness of the engaginghead increases. Thus, even in case of a molded surface fastener composedof very minute engaging elements and having a very high plasticity, thestiffness of its engaging head is secured so as to improve bendingstrength, thereby securing a resistance in the shearing direction.Consequently, there is provided a molded surface fastener of the presentinvention having a desired engagement strength and separation strength.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial plan view showing a first structure example of amolded surface fastener of the present invention;

FIG. 2 is a sectional view taken along the line II-II in FIG. 1;

FIG. 3 is a sectional view taken along the line III-III in FIG. 1;

FIG. 4 is a perspective view showing part of the molded surface fastenerin enlargement;

FIG. 5 is a partial perspective view showing a modification of themolded surface fastener;

FIG. 6 is a partial plan view showing schematically an example of thearrangement of engaging elements in the molded surface fastener;

FIG. 7 is a perspective view showing an embodiment of a preliminaryelement molding cavity for the engaging element;

FIG. 8 is a process explaining diagram showing schematically aproduction process of the molded surface fastener;

FIG. 9 is a partial perspective view showing a specific structureexample of the preliminary element molding cavity of the presentinvention;

FIG. 10 is a plan view showing an embodiment of the preliminary moldedelement;

FIG. 11 is a side view thereof;

FIG. 12 is a front view thereof;

FIG. 13 is a structure explaining diagram showing a modification of thefirst embodiment;

FIG. 14 is a plan view showing a final shape of the molded surfacefastener according to the second embodiment of the present invention;

FIG. 15 is a side view of the molded surface fastener;

FIG. 16 is a partial perspective view of the molded surface fastener;

FIG. 17 is a plan view showing the final configuration of the moldedsurface fastener according to the second embodiment of the presentinvention;

FIG. 18 is a partial perspective view of the molded surface fastener;

FIG. 19 is a structure explaining diagram showing a modification of thesecond embodiment; and

FIG. 20 is a side view showing another modification of the firstembodiment.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, preferred embodiments of the present invention will bedescribed specifically on the basis of embodiments represented indrawings.

FIG. 1 is a partial plan view of a molded surface fastener havingtypical engaging element configuration according to the first embodimentof the present invention. FIG. 2 is a sectional view taken along theline II-II, FIG. 3 is a sectional view taken along the line III-III andFIG. 4 is a perspective view of part of the molded surface fastener asseen from obliquely above.

An engaging element 2 of this embodiment comprises a pillar portion 21rising vertically from a surface of a flat base member 1 and at its topend, an engaging head 22 including a first engaging portion 22 a whichextends in wing-like construction in opposite directions to each other,perpendicular to the molding direction (y direction) and a hook-likesecond engaging portion 22 b which extends in opposite directions toeach other with respect to the molding direction. The pillar portion 21includes a first pillar portion 21 a and a second pillar portion 21 b,which are formed integrally such that they intersect each other at rightangle and all portions from its proximal end to its top end have asubstantially cross shape. Thus, the sectional shape of the pillarportion 21 may be determined arbitrarily, for example, circular,elliptical, just rectangular, polygonal or the like.

According to this embodiment, a dimension W1 of the first pillar portion21 a having a rectangular section in such a direction that it intersectsthe second pillar portion 21 b is set up substantially equal throughoutthe vertical direction. A dimension W2 of the second pillar portion 21 bin a direction that it intersects the first pillar portion 21 a is insuch a manner that its bottom end portion rises such that it curvesmildly in the molding direction and that dimension decreases graduallyfrom halfway of it as it goes toward the top end. By adopting the pillarportion 21 having the cross shaped section, stiffness of the moldedsurface fastener 10 in the molding direction and in a directionintersecting the molding direction can be intensified, so that thissurface fastener is molded unlikely to fall down with respect to apressure generated when the surface fastener 10 is engaged, or when theengagement of the engaging element 2 is released. Because the secondpillar portion 21 b is increased gradually in the molding direction fromits top end to its proximal end, buckling thereof at the proximal endand fall-down of the engaging element 2 can be avoided more whencomparing with a case where it is formed with the dimension from the topend up to the proximal end. According to this embodiment, the thicknessof the base member 1 is 0.1 mm, the height in the vertical direction ofthe first pillar portion 21 a is 0.40 mm, the dimension W1 of the firstpillar portion 21 a in the direction intersecting the molding directionis 0.45 mm, the width W2 of the second pillar portion 21 b in thedirection intersecting the molding direction is all 0.15 mm, an intervalbetween adjacent engaging elements 2 in the molding direction is 1.2 mmand an interval between adjacent engaging elements 2 perpendicularly tothe molding direction is 1.25 mm.

According to this embodiment, from the top end of the pillar portion 21,the first engaging portion 22 a extends substantially horizontally in adirection perpendicular to the molding direction and the second engagingportion 22 b extends in the form of a hook along the molding direction.A pair of the first engaging portions 22 a extending substantiallyhorizontally in the direction perpendicular to the molding directionfrom the pillar portion 21 are constituted of wing-like thin plateshaving substantially same thickness in the vertical direction while thetop surface is of a substantially flat plane as shown in FIGS. 1 and 2.The entire shape of this first engaging portion 22 a provides asubstantially elliptic shape whose ends in the extending direction arecircular as shown in FIG. 1. Further, the width W3 of the first engagingportion 22 a in the molding direction is slightly larger than the widthof the first pillar portion 21 a in the direction. In the meantime,according to this embodiment, the dimension W3 is 0.28 mm, the overalllength in the extending direction is 0.69 mm and the height from thesurface of the base member up to the top surface is 0.5 mm.

On the other hand, the second engaging portion 22 b is formed in a lowerheight than the first engaging portion 22 a and the height of its vertexof the top end is set up substantially equal to or slightly higher thanthe bottom face of the first engaging portion 22 a. Further, the frontend curved in the form of a hook from the top end of the second pillarportion 21 b is oriented toward the surface of the base member 1.According to this embodiment, the height of the vertex of the firstengaging portion 22 a from the base member 1 is 0.4 mm while the heightof the vertex of the second engaging portion 22 b from the base member 1is 0.35 mm. A distance between the front ends of the second engagingportions 22 b in pair extending in opposite directions from the pillarportion 21 is 0.92 mm and as described above, the dimension W3 of thefirst engaging portion 22 a is 0.28 mm. Therefore, the extending lengthof the second engaging portion 22 b projecting from the first engagingportion 22 a is 0.32 mm respectively.

Because the engaging element 2 of this embodiment has theabove-described structure, the thin plate type first engaging portion 22a and the hook-like second engaging portion 22 b, originally likely toengage a pile, which is a mating engaging element, extend in the form ofa cross in the molding direction and a direction perpendicular theretowith respect to the pillar portion. Consequently, they are capable ofengaging the mating pile in all directions and further because part ofthem are the hook-like engaging portions, the engagement force isintensified. Further because there is provided a difference in heightbetween the first engaging portion 22 a and the second engaging portion22 b, they can engage even piles different in height, thereby theengagement ratio being improved.

Because the engaging head 22 is originally supported in the form of across by the first pillar portion 21 a and the second pillar portion 21b through its neck portion, it is not buckled easily at its extending,thereby ensuring an appropriate stiffness. Additionally becauseaccording to the molding method of the engaging element 2 of the presentinvention described later, the engaging head 22 is crystallized morethan the pillar portion 21, the stiffness of the engaging head 22 ishigher than that of the pillar portion.

According to this embodiment, a top central portion 22 c of the engaginghead 22 is slightly dented with respect to the other top surface 22 b.Because the top central portion 22 c′ of the engaging head 22 is dentedslightly more than the other top surface, when it is intended to detachthe pile engaging the engaging element 2, the extended portion becomeseasy to bend along a border between the dented portion and the engaginghead 22 extended from the first pillar portion 21 a due to the dentedportion. Consequently, even if the proximal end portion of the engaginghead 22 is thick in the vertical direction, the pile is easy to detachfrom the engaging head 22 and further, a predetermined separationstrength can be obtained.

According to the above-described embodiment, the engaging head 22including the top end portion of the pillar portion 21 is constructedwith a high stiffness as compared to the flat plate base member 1 andthe pillar portion 21 as described previously and has a constructioneasy to bend when it is separated. Thus, stability of the configurationof the engaging element 2 and holding power for the mating pile areintensified and at the time of separation, an appropriate strength issecured. The dimensions of the respective portions of the engagingelement 2 described previously indicate only the most preferable exampleand those dimensions in relation to the mating pile may be changed invarious ways within a technical scope described in claims and needlessto say, the present invention is not restricted to the above-mentioneddimensions.

The above-mentioned rectangular thin plate type engaging head 22produces various effective functions which cannot be expected toconventional simple upside-down letter J type, letter L type and letterT type engaging elements.

As the first one of those functions, as described previously, the topsurface 22 b of the engaging head 22 can be formed into a flat planethereby eliminating the itchy feeling of the top surface 22 b. Thesecond one is that substantially the stiffness as conventional issecured by such a peculiar shape of the pillar portion 21 with a smallerresin amount than the quantity of resin consumed for the conventionalpillar portion.

The third function is not a function which only allows to engage a hookwhich is curved in the form of a hook like a conventional hook-typeengaging head and having substantially the same thickness, but afunction which allows the mating pile, which is to engage the engaginghead 22, to wind around the top end portion of the pillar portion 21while hooking on the first engaging portion 22 a and the second engagingportion 22 b in pair extended in opposite directions, so thatconsequently the mating pile becomes unlikely to be removed from theengaging head 22, thereby improving the engaging force of the engaginghead 22 largely.

Additionally, according to this embodiment, because the first and secondengaging portions 22 a, 22 b extending from the pillar portion 21 whilecantilevered provide two-leaf style in which the first engaging portion22 a and the second engaging portion 22 b extend in opposite directionsfrom the pillar portion 21, different from a conventional mushroom typeengaging element having an umbrella like engaging head extending in alldirections from the top end of the pillar portion, even if the pilehooks on the top end portion of each pillar portion 21 extendingdownward in a substantially straight line from the bottom face at theproximal end of the paired extending portions such that it windsthereabout, when a force is applied in the direction of separation, boththe first engaging portion 22 a and the second engaging portion 22 b aredeformed elastically so that they are erected via the top end of thepillar portion 21 and the pile moves smoothly along the periphery of theengaging head 22 while receiving a slight friction resistance, so thatit detaches smoothly.

For the reason, the engaging element 2 of this embodiment secures aengaging force sufficiently larger than the separation force ofconventional simple hook type engaging head and as compared to themushroom type engaging head, no cutting occurs on the engaging element 2and the pile and thus, a predetermined engaging force is secured despiteminute dimensions.

Although according to this embodiment, the engaging elements 2 on thecolumn and the engaging elements 2 on adjacent column are disposed justside by side, the engaging elements 2 on the adjacent columns may bedisposed for example, in a staggered style and in this case, a crevicein a direction perpendicular to the engaging element column on the flatbase member 1 can be prevented securely.

Further, although according to the above embodiment, the extendingdirection of the first engaging portion 22 a extending from the pillarportion 21 of the engaging element 2 arranged in the molding directionis all set perpendicular to the molding direction while the extendingdirection of the second engaging portion 22 b is set to the moldingdirection, it is permissible to reverse the extending direction of thefirst engaging portion 22 a and the extending direction of the secondengaging portion 22 b as shown in FIG. 5. Thus, the engaging element 2in which the first engaging portion 22 a extends in a directionperpendicular to the molding direction as shown in FIG. 5 and theengaging element 2 in which the first engaging portion 22 a extends inparallel to the molding direction can be disposed alternately and as forthe entire arrangement, as shown in FIG. 6, it is permissible to disposethe engaging elements 2 whose first engaging portions 22 a extend in thedirection in the staggered style while the engaging elements 2 whosefirst engaging portions 22 a extend perpendicularly to the extendingdirection are disposed in the middle.

The integrally molded surface fastener 10 having such a structure of thepresent invention can be manufactured easily and continuously bychanging part of the structure of the device disclosed in theabove-mentioned Japanese Patent Laid-Open Publication No. 11-56413.

FIG. 8 shows schematically an embodiment preferred as a continuousproduction device for the integrally molded surface fastener and itsproduction procedure.

Reference numeral 111 in the Figure denotes an injection nozzle of thecontinuous injection unit 110. A curved face at the front end of thenozzle 111 has a circular face 111 a having a substantially thecurvature as a cylindrical drum 100, described later. The injectionnozzle 111 is provided with a gap similar to the thickness of the basemember 1 to be molded on that curved face of the cylindrical drum 100.This injection nozzle 111 is formed of T-shaped die and molten resin 11is injected continuously from a resin injection port 111 b formed in thecenter of the front end circular face 111 a at a predetermined resinpressure and a specified flow rate.

Because the basic structure of the cylindrical drum 100 can be obtainedby changing partially the drum structure disclosed in theabove-mentioned Japanese Patent Laid-Open Publication No. 11-56413, thestructure will not be described so much in detail. The cylindrical drum100 is constructed in the form of a hollow drum having a water-cooledjacket 100 a, which serves as an internal cooling means and acircumferential face thereof has a function as a partial molding facefor the molded surface fastener 10. As described above, theaforementioned gap is secured between the circumferential face and thefront end circular face 111 a of the injection nozzle 111 and the axisof the cylindrical drum 100 is set up in parallel to the injection port111 b.

The most important component of the present invention is the rotationdrum 100 and more specifically, the structure of a preliminarily moldedelement molding cavity 101 formed on the circumferential face thereof.The cavity 101 of this embodiment is open in the form of a cross on thecircumferential face of the rotation drum 100 as shown in FIG. 9 and amain cavity 101 a is formed in a straight line up to a predetermineddepth while a second engaging element molding cavity 101 b is formed ata position ⅓ the main cavity 101 a such that it is branched in themolding direction from the center of a long side of a rectangularsection, extended obliquely and curved with its front end directed tothe circumferential face of the drum. The section is rectangular ondeeper side from the position ⅓ from the opening of the main cavity 101a and the sectional area decreases as it goes deeper and the final endterminates with a circular face. Therefore, the entire shape of thepreliminarily molded element molding cavity 101 of this embodimentresembles the shape of a three-pronged lance.

The cylindrical drum 100 in which such cavities are formed in thecircumferential face in large quantities is rotated in one direction andat a time, molten resin 11 is injected continuously from the injectionnozzle 111 toward the circumferential face. Consequently, the basemember 1 is molded on the circumferential face of the drum and thecavity 101 is filled with part of the molten resin, so that apreliminarily molded element 2′ is molded integrally at a time, whichcomprises a preliminarily molded pillar portion 21′ extending linearlyfrom the proximal end portion up to a position ⅓ while having a crossshaped section, and comprises a preliminarily molded head 22′ composedof a preliminarily molded first engaging portion 22 a′ extending fromthe preliminarily molded pillar portion 21′ up to the top end linearlyand hook-like second engaging portions 22 b branching two-way from thetop end of the preliminarily molded pillar portion 21′. A belt-likepreliminarily molded surface fastener 10′ is molded continuously alongthe circumferential face of the rotating cylindrical drum 100.

The preliminarily molded surface fastener 10′ moved and supported by thecircumferential face of the rotating cylindrical drum 100 is cooledaggressively by the water-cooled jacket 100 a incorporated in thecylindrical drum 100 and a cooling water bath 102 in which the lowerhalf of the cylindrical drum 100 is immersed and after that, it ispeeled from the circumferential face of the cylindrical drum 100 by atake-up roller 103 which is a take-up means. The peeled preliminarilymolded surface fastener 10′ is carried to a with-heat pressing portion150 disposed in a next process by upper and lower feed rollers 104 a,104 b.

As shown in FIG. 8A, the with-heat pressing portion 150 extends in adirection perpendicular to the feeding direction of the preliminarilymolded surface fastener 10′ and comprises an ultrasonic horn 150 ahaving a carrying face 150 a′ for supporting the preliminarily moldedsurface fastener 10′ from below and a upper pressing roll 150 b disposedwith a predetermined gap G1 with respect to the carrying face 150 a′.The gap G1 between the ultrasonic horn 150 a and the upper pressing roll150 b is set slightly smaller than the dimension obtained by adding thesetting dimension in the vertical direction of the engaging head 22 to asum of the dimensions in the vertical direction of the base member 1 andthe pillar portion 21 of the molded surface fastener of the presentinvention.

In addition to the construction comprising the ultrasonic horn 150 a andthe upper pressing roll 150 b, the with-heat pressing portion 150 of thepresent invention may comprise a lower supporting member 150 c whose topface acts as a carrying face 150 c′ for the preliminarily molded surfacefastener 10′ and an upper with-heat pressing member 150 d having adownward inclined face 150 e in the feeding direction of thepreliminarily molded surface fastener 10′ as shown in FIG. 8B. In thiscase, a gap G2 which is the narrowest portion between the carrying face150 c′ of the upper with-heat pressing member 150 d and the inclinedface 150 e is set slightly smaller than a dimension gained by adding thesetting dimension in the vertical direction of the engaging head 22 to asum of the dimensions in the vertical direction of the base member 1 andthe pillar portion 21.

FIG. 9 shows a specific structure example of the preliminarily moldedelement molding cavity 101 of this embodiment. In this case, thecylindrical drum 100 is constructed by overlaying plural thin ring-likediscs 100 b coaxially. This Figure indicates a case where a singlepreliminarily molded element molding cavity 101 is formed with threefirst to third ring-like discs 100 b-1 to 100 b-3. In FIG. 9, cut-outsare drawn in larger sizes to facilitate understanding and the respectivering-like discs 100 b-1 to 100 b-3 are represented in smaller thicknessas compared to that size. However, actually the thickness thereof issufficiently larger than the size of the cut-out.

Referring to the Figure, of the three ring-like discs 100 b-1 to 100b-3, the second ring-like disc 100 b-2 sandwiched in the middle is cutout linearly in a predetermined length with a predetermined cut-outwidth along the circumferential direction while that width decreasesgradually. Right and left branches are formed from a positionsubstantially ⅓ from the circumferential face so that circular cut-outsare made with their front ends directed to the circumferential faceside. On the other hand, in the first and third ring-like discs 100 b-1,100 b-3 which sandwich the second ring-like disc 100 b-2, their initialcut-outs width along the circumferential direction are set substantially½ shorter than the width of the initial cut-out in the second ring-likedisc 100 b-2 and become the width as that of a straight cut-out portionin the second ring-like disc 100 b-2 after it passes the circularcut-out in the second ring-like disc 100 b-2, so that a straight cut-outas long as the cut-out thereof is produced.

By overlaying these first to third ring-like discs 100 b-1 to 100 b-3successively and further the ring-like disc 100 b having no cut-out ofthe diameter, the preliminary engaging element molding cavity 101 havingan opening represented by hatching in FIG. 7 is produced. This cavity101 is formed by tilting by 5 to 15° with respect to the rotationdirection of the cylindrical drum 100. As a result of this procedure,when the preliminarily molded surface fastener 10′ is peeled from thecylindrical drum 100, the preliminarily molded element 2′ is erectedupright on the surface of the base member 1.

The drum structure shown in FIG. 9 indicates an example in which it isconstructed by overlaying a plurality of ring-like discs 100 b asdescribed above. Even in case of a cylindrical drum constructed of asingle material, it is easily understood that the cavities 101 havingthe above-mentioned hole structure can be formed all at once at itscircumferential face by mechanical processing, electric dischargemachining or etching processing. In the meantime, the shape of thepreliminarily molded element molding cavity 101 is not restricted to theabove-described one but may be changed appropriately.

The cylindrical drum 100 having such a structure is rotated in adirection indicated with an arrow in FIG. 8A by a well known drive unit(not shown). As described above, the cylindrical drum 100 contains thewater-cooling jacket 100 a internally and the cooling water bath 102 isprovided below the drum 100 so that a substantially lower half of thecylindrical drum 100 is immersed within the cooling water bath 102. Apair of the take-up rollers 103, front and rear, are provided forwardand obliquely upward of this cooling water bath 102 and a trimming unit(not shown) having a cutting means for cutting ears of the belt-likepreliminarily molded surface fastener 10′, which is a raw material forthe molded surface fastener 10 of a final product of the presentinvention, is installed. Additionally, the with-heat pressing unit 150for forming the engaging head 22 is provided forward of the trimmingunit through feed rollers 104 a, 104 b.

According to this embodiment, an ultrasonic tool horn 150 a is adoptedas the with-heat pressing unit 150. It is permissible to use a highfrequency electrode die instead of this ultrasonic horn 150 a. Becausein this internal heating unit 150, only a pressed portion of a resinmolded portion pressed by the pressing roll 150 b is heated locallyinside the resin and deformed, the other portion than that deformedportion is not affected by heating and therefore, the physical propertyof resin molded portion other than the deformed portion does not changerelative to its initial state. Therefore, the present inventioneliminates the necessity of taking into account an influence of heatingupon other portions than the deformed portion which is generated byordinary external heating.

The with-heat pressing unit 150 has an acting face on a carrying routefor the preliminarily molded surface fastener 10′ and supports thecarried preliminarily molded surface fastener 10′ from below. The actingface constitutes the carrying face 150 a′for the bottom face of the basemember 1 of the preliminarily molded surface fastener 10′ which iscarried. The bottom end of the pressing roll 150 b is disposed at aposition lower than a flat plane in which the front end of thepreliminarily molded first engaging portion 22 a′ of the preliminarilymolded surface fastener 10′ passes. The gap setting between theultrasonic horn 150 a and the pressing roll 150 b at this time isdetermined by an interval between the top face of the engaging head 22of the molded surface fastener 10 which is produced and the bottom faceof the base member 1. On the other hand, the top face of the ultrasonichorn 150 a disposed below and opposing the pressing roll 150 b ispositioned on a flat plane in which the bottom face of the base member 1of the preliminarily molded surface fastener 10′ moves.

The supporting position of the pressing roll 150 b can be adjusted witha height adjusting means (not shown) and a heating temperature andheating velocity of the with-heat pressing unit 150 can be controlledeasily with an applied electricity. Further, because rapid heating ispossible different from the external heating with conventional heatingroll or heating plate, secondary molding is possible by synchronizingwith the molding velocity for the primary molded product. Furtherbecause heating can be concentrated locally, the pressing member such asthe pressing roll 150 b can be reduced in size thereby an installationspace being reduced together with the internal heating unit. Thepressing roll 150 b is rotated aggressively by synchronizing with thefeeding speed for a molded product.

The procedure for producing the molded surface fastener 10 of thepresent invention using the production device for the molded surfacefastener having the above-described structure will be describedspecifically based on FIGS. 8 and 9.

The molten resin 11 injected continuously from the injection nozzle 111at a predetermined resin pressure is introduced continuously into a gapformed on the cylindrical drum 100 rotating in one direction. By thisintroduction, the gap is filled with part of the molten resin 11 so asto mold the base member 1 and then, the molten resin is applied to themolding cavities 101 for the preliminarily molded element, formed in thecircumferential face of the cylindrical drum 100 successively and with arotation of the cylindrical drum 100, the preliminarily molded surfacefastener 10′ is molded continuously by molding preliminarily moldedelements 2′ having a peculiar configuration as shown in FIG. 12, whichare a number of primary molded members, on the surface of the basemember 1.

The preliminarily molded surface fastener 10′ having the primaryconfiguration of the surface fastener 10 of the present invention isrotated along a substantially half circumference of the cylindrical drum100 under a guide of the take-up roller 103 and in this while, thepreliminarily molded surface fastener 10′ is cooled aggressively by thewater cooling jacket 100 a from inside of the cylindrical drum 100 whileit passes through the inside of the cooling water bath 102 in whichcooling water at a low temperature (about 15° C.) circulates, so that itis cooled rapidly thereby enhancing the solidification. Because thepreliminarily molded surface fastener 10′ is solidified by this rapidcooling before its crystallization progresses, the base member 1 and thepreliminarily molded elements 2′ entirely have much plasticity.

When the preliminarily molded surface fastener 10′ after thissolidification ends is taken by the paired feed rollers 104 a, 104 b,upper and lower ones, through the take-up roller 103, each preliminarilymolded element 2′ having the configuration shown in FIGS. 10 to 12 ispulled out from the cavity 101 smoothly while deformed elastically. Topeel out the preliminarily molded surface fastener 10′ molded in thisway from the cylindrical drum 100, the paired feed rollers 104 a, 104 b,upper and lower ones, which rotate in opposite directions synchronouslywith each other as described above are used. Although the feed rollers104 a, 104 b may have a smooth circumferential face, if a plurality ofrows of guide grooves extending along the circumference foraccommodating and guiding the preliminarily molded element 2′ are formedin the circumferential face or an elastic layer (not shown) is formed ofmild urethane thereon, much convenience can be expected because thepreliminarily molded element 2′ may not be damaged in vain.

The preliminarily molded surface fastener 10′ molded on thecircumferential face of the cylindrical drum 100 has a number of thepreliminarily molded elements 2′ erected substantially vertically from asurface of the base member 1. According to this embodiment, as shown inFIGS. 10 to 12, each of the number of the preliminarily molded elements2′ comprises the preliminarily molded pillar portion 21′ having a crossshaped section up to a height of substantially ⅓ from its proximal endposition and the preliminarily molded head 22′, which is composed ofpreliminarily molded first engaging portions 22 a′ having a longrectangular section in the direction perpendicular to the moldingdirection and extending linearly from the top end of the preliminarilymolded pillar portion 21′ along the same axis line as the preliminarilymolded pillar portion 21′, and paring preliminarily molded secondengaging portions 22 b′ branched in two ways back and forth in themolding direction from the top end of the preliminarily molded pillarportion 21′.

Upon molding the preliminarily molded element 2′, the height of thepreliminarily molded first engaging portion 22 a′ from the base member 1is set higher than the height of the preliminarily molded secondengaging portion 22 b′ from the base member 1 taking into account adeformation amount of the preliminarily molded first engaging portion 22a′. Then, the preliminarily molded first engaging portion 22 a′ isdeformed into a thin plate which stretches to the right and left sideslike wings by pressing with heat from above with the with-heat pressingunit 150. At this time, only the preliminarily molded first engagingportion 22 a′ is pressed with heat by the with-heat pressing unit 150according to this embodiment and no pressure with heat is applied to thepreliminarily molded second engaging portion 22 b′. Therefore, thepreliminarily molded pillar portion 21′ and the preliminarily moldedsecond engaging portion 22 b′ keep their original configurations andturn to the pillar portion 21 and the second engaging portion 22 brespectively at the time of completion.

After the ear portions existing on the right and left sides in widthdirection are cut out with the trimming unit (not shown), thepreliminarily molded surface fastener 10′ molded by the cylindrical drum100 is introduced in between the ultrasonic horn 150 a and the pressingroll 150 b of the with-heat pressing unit 150 through the feed rollers104 a, 104 b. When the preliminarily molded head 22′ passes between theultrasonic horn 150 a and the upper pressing roll 150 b, heat isgenerated from inside of the top end portion of the preliminarily moldedfirst engaging portion 22 a′ pressed by the pressing roll 150 b under avibration of the ultrasonic horn 150 a, so that when it passes thewith-heat pressing unit 150, from the top end to the top face of thepreliminarily molded second engaging portion 22 b′ is melted anddeformed. Consequently, a flat wing-like thin first engaging portion 22a is molded such that its top face is of a substantially flat plane,which is slightly larger than the width of the first pillar portion 21 aand extends in the direction of a long side of the first pillar portion21 a.

After as described above, the first engaging portion 22 a is softenedwith a heat by the ultrasonic horn 150 a and deformed into asubstantially wing-like thin plate by pressing, its crystallizationprogresses at its heated portion by gradual cooling and solidification,so that the stiffness of the first engaging portion 22 a becomes higherthan those of the pillar portion 21, the base member 1 and the hook-likesecond engaging portion 22 b. Consequently, because of the base member 1and the engaging element 2 of the preliminarily molded surface fastener10′ possessing excellent plasticity due to rapid cooling andsolidification, only the first engaging portion 22 a has a higherstiffness than the other portions, in case of even the engaging element2 of the molded surface fastener 10 having an extremely high plasticitydespite its minute dimension, the hook-like second engaging portion 22 bhaving a high engaging force because of its shape possesses theplasticity as the pillar portion 21 while the stiffness of the firstengaging portion 22 a is secured. As a result, a holding force in theseparation direction to the mating pile is secured.

Even the molded surface fastener 10 having both characteristics,plasticity and minute engaging element configuration which the presentinvention proposes provides a high quality product which ensures anexcellent tactile feeling and extremely stabilized configurationsecuring a predetermined engaging force and can bear repeated usage ofseveral times sufficiently.

The shape of the engaging head 22 as seen in a plan view molded at thistime as shown in FIG.1 provides a cross shape produced by therectangular first engaging portion 22 a having circular front endportions and a short strip-like second engaging portion extendinglinearly intersecting this. Consequently, the pillar portion 21 of theengaging element 2 is composed of the first and second pillar portions21 a, 21 b, extending in the molding direction and the directionperpendicular to that direction respectively with the cross-shapedsection. Because the first and second engaging portions 22 a, 22 b aresupported independently as if they are cantilevered by the pillarportion 21, substantially, the structure as four-leaf hook type engaginghead is produced and thus, various problems accompanying the mushroomtype engaging element such as a stronger separation strength thannecessary and hanging by a pile never occur.

Although the present invention has been described about a case where theextending direction of the first engaging portion 22 a from the pillarportion 21 is in a direction perpendicular to the molding direction, ifthe main cavity 101 a of the molding cavity 101 for the preliminarilymolded element 2′ is formed to be longer along the molding direction andthe hook-like second engaging portion molding cavity 101 b is formed soas to extend perpendicularly to the molding direction, the extendingdirections of the first engaging portion 22 a and the second engagingportion 22 b can be changed. Thus, if the cavities 101 are formed in thecircumferential face of the cylindrical drum 100 by mixing thesedirections as shown in FIG. 5, it is possible to produce the moldedsurface fastener 10 mixed with the engaging heads 22 in which theextending directions of the first engaging portion 22 a and the secondengaging portion 22 b are reverse to each other as shown in FIG. 6.

FIG. 13 shows the configuration of the molded surface fastener 10according to a modification of the above embodiment. It is understoodthat the front end portion of the first engaging portion 22 a of thefirst embodiment is bent downward. That is, according to thismodification, the first engaging portion 22 a is not molded in the formof a mere flat plate but by curving the front end of the extending sidedownward in the form of a hook, a curved portion 22 d is formed so as toincrease the engaging strength and separation strength with the matingpile up to a desired strength. To curve the front end of the engaginghead 22 downward in the form of a hook, when the preliminarily moldedelement 2′ of the preliminarily molded surface fastener 10′ molded bythe cylindrical drum 100 is melted and deformed under a pressure by thewith-heat pressing unit 150, the frequency of the ultrasonic horn is setso that the internal heating in the element material is higher thannormal, or the diameter of the pressing roll 150 b is enlarged so as toset up a relatively longer pressing time. Consequently, softening of thefront end portion of the first engaging portion 22 a progresses so thatit is curved by its own weight.

Further, the present invention includes a case where the quantity ofdeformation of the preliminarily molded first engaging portion 22 a′ inthe pressing direction is increased in the with-heat pressing portion150. In this case, the top surface of the preliminarily molded secondengaging portion 22 b′ of the preliminarily molded head 22′ is meltedand deformed by pressing so as to form the top face into a flat planeand an expanded portion is formed by expanding slightly in the widthdirection horizontally from that flat plane. As a result, the secondengaging portion 22 b has the flat top face in addition to its hookshape and includes right and left expanding portions which expand in thewidth direction. Thus, in addition to the engagement strength with themating pile, the separation strength is also increased.

FIGS. 14 to 16 show the second embodiment of the present invention.According to this embodiment (not shown), on the preliminary moldingstage, the preliminarily molded first engaging portion erected linearly,which is a composition of the preliminarily molded element, is dividedto ½ sections in the direction perpendicular to the molding direction(right and left) and for each section, hook-like preliminarily moldedsecond engaging portions are extended in parallel to each other inopposite directions to each other along the molding direction from thefirst engaging portion.

By passing the preliminarily molded surface fastener having thepreliminarily molded element 2′ having such a configuration through thewith-heat pressing unit 150 shown in FIG. 8, which is a producingportion, the engaging element 2 having a configuration shown in FIGS. 14to 16 is molded. For this engaging element 2, by pressing thepreliminarily molded first engaging portion of the preliminarily moldedelement from above with heat so as to melt (or soften) and deform, thefirst engaging portion 22 a with the wing-like thin plate stretched tothe right and left sides is molded. In case of this embodiment also, thepreliminarily molded second engaging portion does not undergo pressingand deformation by the with-heat pressing unit 150, and its ownconfiguration is maintained so as to produce the hook-like secondengaging portion 22 b.

FIGS. 17 and 18 show the third embodiment of the present invention. Asfor the configuration of the engaging element 2 of this embodiment, asunderstood from the figures, a pair of the second engaging portions 22 bextending in parallel back and forth in one direction are formed and thefirst engaging portion 22 a composed of wing-like thin plate extends tothe right and left across the right and left second engaging portions 22b in pair.

FIGS. 19A and 19B show a further modification of the second embodiment.According to this modification, the first engaging portion 22 a composedof the wing-like thin plate and the second engaging portion 22 bcomposed of hook piece are disposed such that they intersect at rightangle as seen in a plan view and they provide a substantially letter Lshape because they extend in each single direction with respect to thepillar portion 21 as seen in a top view. In case of this modification,because the first engaging portion 22 a and the second engaging portion22 b do not intersect like a cross like the above-described firstembodiment, the engagement ratio with the mating piles decreases andtherefore, a gap between adjacent engaging elements 2 is preferred to besmaller than the first embodiment.

FIG. 20 shows a further modification of the first embodiment. Accordingto this modification, the preliminarily molded second engaging portion22 b′ is not molded into a hook whose front end curves toward thesurface of the base member 1 on the preliminary molding of the engagingelement 2, but molded so that it rises linearly and obliquely upwardfrom the top end of the second pillar portion 21 b with a mild gradient.Then, the top surface of this molded preliminarily molded secondengaging portion 22 b is pressed with heat by a predetermined amountwith the preliminarily molded first engaging portion 22 a′ so as to melt(soften) and deform. As a result, as shown in FIG. 20, the top face ofthe second engaging portion 22 b turns to a flat plane and the expandingportions 22 b-1 which expand horizontally to the right and left fromthis flat plane are formed. This expanded portion 22 b-1 supplements areduction of an engagement force, which results from that theconfiguration of the second engaging portion 22 b turns to the hookshape extending linearly, so as to secure a desired engagement force.Additionally, the aforementioned flat surface improves the itchy feelingof the surface of that surface fastener.

The second and third embodiments and the modifications exert theoperation and effect as the first embodiment. The above-mentionedembodiments and modifications are typical examples of the presentinvention and, needless to say, may be modified in various ways by thoseskilled in the art.

1. An integrally molded surface fastener of synthetic resin in which anumber of fine engaging elements, which engage/disengage a mating pilepiece, are molded integrally on a surface of a flat base member, whereineach engaging element comprises a pillar portion having a predeterminedheight and an engaging head composed of first and second engagingportions, which extend from a top end of the pillar portion along thesurface of the base member in a first direction (x) and in a seconddirection (y) different from the first direction, and the first andsecond engaging portions have different shapes.
 2. The integrally moldedsurface fastener according to claim 1, wherein the first engagingportion is constituted of a pair of wing-like thin plates whichintersect with the second engaging portion at right angle and extend inopposite directions across the top end of the pillar portion.
 3. Theintegrally molded surface fastener according to claim 2, wherein a frontend of the first engaging portion substantially droops toward thesurface of the base member.
 4. The integrally molded surface fasteneraccording to claim 2, wherein the second engaging portion is constitutedof one or more engaging pieces which substantially intersect with thefirst engaging portion at right angle across the top end of the pillarportion and extend in opposite directions each other.
 5. The integrallymolded surface fastener according to claim 1 or 2, wherein the secondengaging portion is constituted of a hook piece and a front end of whichis curved toward the base member.
 6. The integrally molded surfacefastener according to claim 1, wherein the pillar portion has ahorizontal section which intersects with the first direction (x) and thesecond direction (y) of the first and second engaging portions in a samedirection.
 7. The integrally molded surface fastener according to claim1 or 2, wherein a central portion of a top face of the engaging head isslightly dented.
 8. The integrally molded surface fastener according toclaim 1, wherein there is a difference in distance between a distancefrom the surface of the base member to a front end of the first engagingportion and a distance to a front end of the second engaging portion. 9.The integrally molded surface fastener according to claim 1 or 2,wherein the first engaging portion is disposed perpendicularly to amolding direction of the base member while the second engaging portionis disposed in parallel to the molding direction of the base member. 10.A method of production for the integrally molded surface fasteneraccording to claim 1, comprising: rotating a cylindrical drum in onedirection, the cylindrical drum having a number of preliminarily moldedelement molding cavities each composed of a main cavity which is open ina circumferential face and extends linearly up to a predetermined depthand a second engaging portion molding cavity which is not open in thecircumferential face and is branched from halfway of the main cavity andextends in a molding direction or in a lateral direction with respectthereto; injecting molten resin continuously to the circumferential faceof the cylindrical drum, molding the base member along thecircumferential face while molding a number of preliminarily moldedelements on a back side of the base member such that they erect upright;peeling a belt-like preliminarily molded surface fastener from thecircumferential face of the cylindrical drum, the preliminarily moldedsurface fastener having the preliminarily molded elements on the basemember which moves carried by the circumferential face of the rotatingcylindrical drum; feeding the preliminarily molded surface fastenerpeeled continuously to a with-heat pressing portion; and pressing atleast a preliminarily molded first engaging portion erected linearly ofthe preliminarily molded elements erected integrally from the surface ofthe base member of the carried preliminarily molded surface fastenerwith heat, melting and deforming into a flat wing-like thin plate so asto mold the first engaging portion successively.
 11. The method ofcontinuous production for the integrally molded surface fasteneraccording to claim 10, further comprising: melting and deforming thepreliminarily molded first engaging portion into the flat wing-like thinplate by pressing the with-heat pressing portion with heat; and meltingand deforming a top end of a preliminarily molded second engagingportion at a time.
 12. A continuous production device for the integrallymolded surface fastener according to claim 1 comprising: a cylindricaldrum rotating in one direction and having a number of preliminarilymolded element molding cavities composed of a main cavity which is openin a circumferential face and extends up to a predetermined depth and asecond engaging portion molding cavity which is branched from halfway ofthe main cavity and extends in a molding direction; a continuousinjecting unit which injects molten resin continuously to thecircumferential face of the cylindrical drum so as to mold the basemember along the circumferential face, and molds a number ofpreliminarily molded elements on a back side of the base member suchthat they are erected upright; a take-up roller for peeling a belt-likepreliminarily molded surface fastener from the circumferential face ofthe cylindrical drum continuously, the preliminarily molded surfacefastener having the preliminarily molded elements on the base memberwhich moves carried by the circumferential face of the rotatingcylindrical drum; and a with-heat pressing portion which presses withheat at least a preliminarily molded head erected linearly of thepreliminarily molded elements erected integrally from the surface of thebase member of the peeled preliminarily molded surface fastener so as tomelt and deform into a wing-like thin plate to mold the first engagingportion successively.
 13. The continuous production device according toclaim 12, wherein the with-heat pressing portion comprises an internalheating unit containing a carrying face for the preliminarily moldedsurface fastener and a rotation roll containing a rotation shaft whichis included in a plane above and in parallel to the carrying face andextends in a direction perpendicular to a feeding direction of thepreliminarily molded surface fastener, and a gap between a bottom endposition of the heating rotation roll and the carrying face is setsmaller than a dimension gained by adding a setting dimension in avertical direction of the engaging head to a sum of dimensions in avertical direction of the base member and the pillar portion.
 14. Thecontinuous production device according to claim 12, wherein thewith-heat pressing portion comprises a carrying face for thepreliminarily molded surface fastener and is disposed above the carryingface, and further comprises a with-heat pressing member having aninclined face in which a gap between a bottom face thereof and thecarrying face decreases gradually, and a gap of a narrowest portionbetween the carrying face and the inclined face is smaller than adimension gained by adding a setting dimension in a vertical directionof the engaging head to a sum of the dimensions in a vertical directionof the base member and the pillar portion.